1. Field of the Invention
The invention relates to a motor-driven fire door, particularly a two-sided fire door, having an automatic closing feature.
2. Description of the Related Art
Two-sided fire doors have first and second doors which are movable toward each other to close the doors and away from each other to open the doors. The doors each include a plurality of panels which are suspended from a head track by trolleys and are hinged together so that they can pivot relative to each other. Where adjacent panels are hinged to pivot in opposite directions so that the panels can fold against each other to form a stack, the door is referred to as an accordion-type door. Where adjacent panels are hinged to pivot in the same direction so that the door can travel around curves and be wound onto a coil, the door is referred to as a sliding door. In both cases the doors are driven by respective motors and acted on by respective weights to draw them closed when power to the motor and/or brake from the fire alarm or smoke detection system is interrupted. As such, a two-door system requires two motors and two sets of weights (or a battery backup system) or other mechanism urging toward a closed position or, in some cases, toward an open position.